Metrics
Updated
Bounce rate
Definition
Email bounce rate is the percentage of sent emails that the receiving server rejected as undeliverable. It is usually split into hard bounces (permanent) and soft bounces (temporary).
How it works
Bounce rate = bounced emails / sent emails x 100. When people quote a bounce rate threshold, they almost always mean the hard (permanent) bounce rate, because soft bounces are retried and often delivered later.
A bounce is reported either during the SMTP conversation (the server rejects with a 5xx or 4xx code) or afterwards as a bounce message (a non-delivery report) sent to the envelope sender address.
Example
1.5% is under the commonly used 2% warning line.
Why it matters
Mailbox providers read a high hard bounce rate as a sign that a list was bought, scraped or left to rot. It damages sender reputation and can get sending paused by your ESP.
A rising bounce rate is often the first visible sign of a bad import, long before complaints show up.
Benchmarks
- Remove hard bounces after the first occurrence. Mailing a non-existent address again only adds negative signals.
- Confirm new signups with double opt-in so typos never enter the list.
- Verify old or imported lists before the first send, and send to a small engaged segment first.
- Track bounce rate per send, not only as a monthly average, so one bad import is visible.
| Hard bounce rate | What it usually means | Action |
|---|---|---|
| Under 1% | Healthy, opt-in list | Keep suppressing bounces |
| 1% to 2% | Some aging data | Clean before the next large send |
| 2% to 5% | Old or unverified addresses | Stop and clean the list |
| Over 5% | Imported or purchased data | Pause sending to that list |
How Lumail handles bounce rate
Lumail suppresses an address automatically after a permanent bounce, so it is never mailed again. In Settings, Deliverability you see bounce windows per period.
When the sustained permanent bounce rate goes above 2%, Lumail raises a warning. Above 5% it is an error. Low-volume days stay neutral so one small send does not trigger alerts.
Check a real message with the free mail tester or the spam tester.
Frequently asked questions
What is a good email bounce rate?
Under 2% hard bounces per send is the common healthy threshold, and well-maintained opt-in lists usually stay under 1%. Above 5% means the list has a serious data problem.
Should soft bounces count in my bounce rate?
Track them separately. Soft bounces are temporary and retried. Repeated soft bounces to the same address over several sends should be treated like a hard bounce.
Will sending more email lower my bounce rate?
No. Diluting the rate with more mail does not remove bad addresses, and providers see the absolute volume of failures. Remove the bad addresses instead.
Related terms, tools and docs
- DeliverabilityHard bounceA hard bounce is a permanent delivery failure: the receiving server rejected the email and retrying will not help.
- DeliverabilitySoft bounceA soft bounce is a temporary delivery failure: the receiving server deferred the email but the address may accept it later.
- List managementList hygieneList hygiene is the routine of removing or suppressing email addresses that hurt deliverability: hard bounces, spam complainers, long-inactive subscribers, invalid addresses and likely spam traps..
- List managementDouble opt-inDouble opt-in (confirmed opt-in) is a signup process where a new subscriber must click a link in a confirmation email before they are added to the list.
- Free toolFree mail testerSend a real email and get an SPF, DKIM, DMARC and content report.
- Free toolFree spam testerCheck an email for the patterns that push mail to spam.
- DocsHow to lower bounce rateWhat to do when permanent bounces pass 2% or 5%.
- DocsEmail verification APICheck an address before you add it.
- DocsSender healthHow Lumail measures sending health and authentication.
Browse every definition in the email marketing glossary.
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